Electrical switch



ELECTRICAL SWITCH Original Filed April 5, 1945 1 INVENTDR Euwnnn EBuLLADJII of the order required in the machine Patented Dec. 30, 1952 UNITED STATE ELECTRICAL SWITCH Edward P. Bullard,

Connecticut Original application Divided an III, Fairfleld, Conn" assignor to The Bullard Company,

a corporation of April 5, 1945, Serial No.

d this application November 18, 1947, Serial No. 786,772

8 Claims.

This invention relates to electric circuit-making switches, and particularly to a new and improved switch that is capable of repetitive use with extremely accurate results. This is a division of application serial Number 586,799, filed April 5, 1945, now Patent No. 2,511,821, dated June 13, 1950, which itself is a division of Application Serial Number 541,986, filed June 24, 1944, now Patent No. 2,528,736, dated November '7, 1950, all in the name of Edward P. Bullard, III.

Ordinarily, the accuracy that can be obtained in the operation of machine tools, and particularly in the automatic-cycle operation of machine tools is limited by the accuracy that can be obtained with certain essential elements of the automatic control. For example, when electrical circuits are employed to control the movement of a member, the accuracy that can be obtained is limited by the accuracy ofv the operating parts of the electrical circuit, and particularly by the accuracy of those part which are utilized repeatedly to efiect stopping of the movement of the member such as trip switches.

Machine tool operation requires an accuracy, in stopping the movement of a tool, in the nature of .0005 of an inch. Not only must such accuracy be produced, but it must consistently be maintained regardless of the rate at which the tool is moved. Prior known electrical devices including contact-making switches for controlling the movement of a tool fail to produce accuracies tool control as set forth above.

Certain prior-known switches employ metalflexing members that can be operated in response to tool movement. The accuracy of such switches is limited because the metal-flexing member fails to respond at exactly the same point of tool movement upon repeated operations under the same conditions. Plunger-type switches of the prior art are not reliable because their accuracy is directly affected by the action of the movable member that operates them. All prior-known switches are of relatively large size so that employment of any substantial number such as thirty or forty of such switches in a unit becomes impractically large and cumbersome. An additional disadvantage of prior-known plunger-type switches is that the impact between the plunger and its movable actuator materially affects the accuracy of the switch often causing the contacts to close prematurely.

Objects of the present invention include the provision of an electrical circuit-making switch that will overcome the above as well as other disadvantages of prior-known switches; the provision of a plunger-type electrical switch in which the plunger is moved to contact-making position by a device designed to provide a minimum of side thrust to the plunger; the; provision of: such a switch in which the contact-making action thereof is independent of the impact incident to switch actuation by a movable member: the provision of such a switch in which the plunger velocity increases from a minimum as it moves toward contact-making position; the provision of such a switch in which as many as forty can be arranged side by side in a space in the neighborhood of ten inches; and the provision of such a switch which can be operated'with equal facility by a movable member approaching it from either of two directions.

The above. as well as other objects and novel features of the invention, will become apparent from'the following specification and accompanying drawing, in which:

Figure l is an elevational view of an electrical circuit-making switch to which the principles of the present invention have been applied;

Fig. 2 is a view of the apparatus shown in Fig.

l, as viewed when looking in the direction of the,

arrows 2-2 of Fig. 1;

Fig. 3 is a view of the apparatus shown in Fig. l, as viewed when looking in the direction of the arrows 3--3 of Fig. 1; and

Fig. 4 is a perspective view of a detail of the switch.

The embodiment disclosed in the present case deals with the employment of a relatively large number of switches arranged in closely spaced relation. and to separate actuators" for each switch, which latter are adjustable throughout the entire path of travel of a movable member controlled by the operation of the switches.

Referring to Fig. 1, supports l0 and II are spaced apart an amount proportionaLand preferably equal to the total distance of movement of a movable machine tool member towhich an arm I! of insulating material is rigidly attached. A metallic body I3 is fixed to the arm l2 and is provided with a series of cylindrical passages [4 arranged in closely spaced aligned relation for the reception of individual plunger contacts 15 of separate switches. The present embodiment of'the invention utilizes in the neighborhood of forty switches which are unitarily movable, with the member to be controlled. between the supports ill and H. It is evident. therefore, that a main consideration of the design of the switches is that as many as forty or more may be mounted for movement with the movable member and still consume little space. Actually, inthe practical embodiment, passages M are located on inch centers. Since all of the switches are identical, only one will specifically be described.

Each plunger I5 is provided with a portion 16 of reduced diameter that extends upwardly through a hole [1, within the arm 12, that is aligned with a passage [4. Spring 18 surrounds the reduced diameter portion l6 of plunger and is compressed between the arm l2 andthe shoulder between the large and small diameter portions of plunger I5. Spring contact members [9 for adjacent plungers l5 are arranged on alternative sides of the arm l2; and each is provided with a contact that'overlies the top of an opening l1. Accordingly, spring I8 urges plunger 15 out of contact-making position; and axial movement of plunger IS in opposition to the action of spring I 8 'effects'contact between the end of plunger [5 and contact 2!]. In order to insure uniform action of plunger l5 under the same operating conditions, it has been found important to eliminate as much as possible side thrust between the plunger 15 and the hole [4 within which it reciprocates. Excessive side thrust at this location causes unpredictable action of plunger l5 especially when wear between the plunger and hole occurs incident to such side thrust.

As previously stated, the "diameter of plunger l5 must be relatively small so that a plurality of switches consume relatively little space. Should plunger l5 be moved axially by the usual impact between it and a member moving'at right angles to the axis of the plunger l5, excessive unit side thrust would occur between plunger l5 and hole l4 causing excessive wear with attending error in switch actuation.

"the plunger l5 must not be subject to a sudden start of motion as is common in prior known plunger switches where impact between the plunger and a movable member is relied upon. Such sudden starting of the plunger, particularly when excessive side thrust is present, often causes the plunger to In the present invention all of the above considerations have been 'taken into account in designing an actuator for moving the plunger I5 jump ahead and pre- 'maturely close the switch contacts.

axially when the actuator is subject to a force at right angles to the axis of plunger l5. In

other words, the electrical switch is so designed that the plunger I5 is moved by an'actuator into circuit-making position along a path at right angles to the relative movement between 'the switch and a trip dog, during plunger movement and prior to circuitmaking condition, is not subjected to any force at right angles to said relative movement "beand in which thetrip dog,

tween the switch and'dog. ,Referringto Figs. 1 i and 3, the lower portion of body 13 is provided with slots 2| aligned with the passages 14 form- 'ceiving plunger actuators 22 (Fig. '4'). The a'ctuators 22 include thin plate-like-members hav- "ing an arcuate edge portion 23 and tangential surfaces 24 extending therefrom. The actuators 22 are adapted to be assembled and dis-assembled from the body I3 without the use ofseparate fastening means, by trunnions 2'5, 25' that extend outwardly from each face. The form of the lower portion of base [3 includes recesses 26, 26' on each side thereof adapted toreceive trunnions 25, 25; and shoulders '21, 2'! are provided for supporting the trunnions in fixed'position against the action of spring H3.

The one side of member l3 at the-location of the recess 26' is further relieved by an'undercut 28 for receiving the trunnions 25' during assembly '25 on shoulder 21.

and disassembly of the actuator 22. The position of the trunnions 25, 25' during assembly and disassembly is shown in dotted lines in Fig. 1. With trunnions 25' within the undercut 28, it is evident that the trunnions 25 can be pivoted about trunnions 25 in a manner to permit trunnions 25 to clear the shoulder 21. Upon movement of the actuator 22 in a manner to locate trunnions 25 on shoulder 21, trunnions 25' are forced out of the undercut '28, whereupon spring l8 seats trunnions Disassembly of the actuator 22 is efiected by a reverse of the action above described.

An abutment element 29 is integral with, and extends downwardly from the actuator 22. It is adapted to receive the impact from a dog 30 that is adjustable throughout the length of travel of a movable member to which the arm I2 is attached. The dog 3!] is rectangular in "construction, and can be approximately as thick as the distance between centers of the plungers I5. It is only essential that the dogs clear adjacent dogs permitting them to pass each other during adjustment. Each dog 30 is provided with parallel off-set passages 3|, 32 adapted to receive wires 33 and 3 respectively. The wire 34 is rigidly mounted between supports I8, ll, while the wire 33 is adjustably mounted between said supports. The wire 33 extends beyond both supports l6 and II and a spring'35 surrounds the one extension between the support it! and. a nut 36. The opposite end of wire 33 is provided with a screw thread of 43 threads per inch and a micrometer nut 3'] is threaded onto said threaded extension into engagement with support H. Each dog30 includes two threaded openings 38,39 into which screws 50, 4| are threaded, and whichlatter engage wire 33l0cking dog 36 thereto. Referring to Fig. 3, it is evident that wires 33 and 34 are ofiset. The reason for this is that adjacent dogs 39 are provided with alternate locationsfor wires 33 and 34. Thus, the first dog 36 on the left of Fig. 3 has wire 33 at the bottom and wire 34 at the top; while the second dog 33 from the left of Fig. 3, has wire 33 at the top and wire 34-at the bottom. This permits locating the micrometer nuts for adjacent dogs 30 in overlying relations which thereby consume less space. This necessitates using alternately long and sh'ort'set screws 48, 4| in adjacent dogs 3!! so that in each instance the dog 30 is locked to the wire 33.

The surfaces 42 and 43 of dogs 38 areparallel and normal to the direction of motion of the member to which arm I 2 is attached. Accordingly, an abutting'engagement between the element 29 and either surface 2 or "#3 always occurs totally within a surface that is at right angles to the direction of relative movement between the dog 39 and the member to which arm I2 is attached. Accordingly, from the time of contact between dog 3!] and element 29, until contact between 25 and the end of plunger l5 occurs, there is no vertical force acting on dog 3!]. This is important to ensure repetitive operation of contact 2B and plunger [5 at exactly the same, point.

7 The construction and arrangement of the various parts are such that the dog 35 may initially .be set roughly by loosening screws 39, ll and Movement of the member to which arm 12 is attached so that abutting engagement occurs between element 29 and surface 42 causes trunnions 25 to seat on shoulder 21, and actuator 22 to pivot on trunnions 25. This pivotal action causes the arcuate surface 23 and tangential surfaces 24 to force plunger 15 upwardly until contact is established between plunger 15 and contact 20. From an inspection of Fig. 1, it is evident that, by virtue of the arcuate surface 23, the initial pivotal movement of actuator 22 causes initial upward movement; of plunger at a relatively slow rate, gradually increasing due to the increasing distance between the point of contact of plunger l5 and actuator 22, and the trunnions 25. For this reason, any severe impact between surface 42 and element 29 is transferred into a rolling action about trunnions 25 in a manner such that plunger 15 initially begins to move upwardly at a slow rate which is independent of the impact between the surface 42 and element 29.

Should the switch move in a direction such that element 29 abuts surface 43, the same action occurs with actuator 22 pivoting about trunnions 25'.

Since the actuator 22 pivots when impact occurs between element 29 and surfaces 42 or 43, the side thrust of plunger I5 in passage [4 is independent of such impact or abutment force. Accordingly, the plunger I5 can be made as small in diameter as desired without building up a detrimentally-high unit side thrust pressure between it and passage 14 which occurs in priorknown plunger-type switches.

Although the various features of the improved switch have been shown and described in detail to fully disclose one embodiment of the invention, it will be evident that numerous changes can be made in such details, and certain features can be used without others, without departing from the principles of the invention.

What is claimed is:

1. An electrical switch comprising in combination, a body; a plunger mounted within a bore of said body for reciprocable motion; a slot in said body in line with said plunger; contact closing means comprising a fiat plate adapted to be freely received by said slot; and pivot means between said body and said plate.

2. An electrical switch comprising in combination, a body; a plunger mounted within a bore of said body for reciprocable motion; a slot in said body in line with said plunger; contact closing means comprising a flat plate adapted to be freely received by said slot; and trunnions on said plate adapted to be supported by said body.

3. An electrical switch comprising in combination, a rigid body; a plunger mounted within a bore in said body for reciprocable motion such that its one end may move from within to the outside of said body; one part of a single contact means resiliently urged against said rigid body and adapted to cover the bore in which said plunger reciprocates; a slot in said body in line with said plunger; a flat plate freely movable within said slot; spaced trunnions on said plate adapted to be supported by said body; and means for resiliently urging said plunger into engagement with the edge of said plate.

4. An electrical switch comprising in combination, a rigid body; a plunger mounted within a bore in said body for reciprocable motion such that its one end may move from within to the outside of said body; one part of a single contact means resiliently urged against said rigid body and adapted to cover the bore in which said plunger reciprocates; a slot in said body in line with said plunger; a flat plate freely movable within said slot; spaced trunnions on said plate adapted to be supported by said body, the overall dimension of said plate including its thickness and the length of said trunnions being no greater than the maximum diameter of said plunger; and means for resiliently urging said plunger against an edge of said plate.

5. An electrical switch comprising in combination, a body; single contact means; means responsive to multi-directional forces for closing said contact means, including a flat relatively thin plate having spaced trunnions; a slot in said body for freely receiving said plate; undercut portions on each side of said body for receiving and guiding said trunnions; and an additional under-cut portion associated with one of said guiding portions adapted to receive one of said trunnions, whereby said plate may be assembled to said body.

6. In a switch, a body; a passage in said body; a plunger within said passage; a contact adapted to be engaged by said plunger when the plunger is moved axially within said passage; means for administering an axial thrust to said plunger when said means is subjected to a force normal to the longitudinal axis of said plunger including a thin plate-like actuator; spaced trunnions extending from each face of said actuator; seating means on said body for receiving said trunnions; and resilient means for maintaining said plunger in engagement with said actuator.

7. In a switch, a body member; a passage within said body member; a plunger within said passage; means for transferring a forc normal to the longitudinal axis of said passage to, and axially of said plunger comprising a plate-like actuator having an arcuate edge surface; spaced sets of trunnions on said actuator; shoulders on said body member for supporting the trunnions of said actuator, said body member being recessed above said shoulders whereby said actuator may be pivoted about either set of trunnion s; and a spring for maintaining said plunger in engagement with the edge of said actuator.

8. In a switch, a body; a passage within said body; a plunger within said passage; means for administering an axial thrust to said plunger comprising a plate-like actuator having an arcuate edge surface; spaced sets of trunnions on said actuator; shoulders on said body for supporting the trunnions of said actuator; a passage associated with one of said shoulders and adapted to receive one set of said trunnions during assembly and disassembly of said actuator and body; and a spring for maintaining said plunger in engagement with the edge of said actuator.

EDWARD P. BULLARD, III.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 983,610 Dooley Feb. 7, 1911 1,342,591 McNicholas June 8, 1920 1,540,400 Kellan June 2, 1925 1,736,746 McShane Nov. 19, 1929 1,952,153 Young Mar. 27, 1934 2,133,545 Krieger Oct. 18, 1938 2,255,706 Height Sept. 9, 1941 2,276,740 591150 Mar. 17, 1942 

